Re: [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Paolo Bonzini <pbonzini@redhat.com>]

Il 29/07/2014 15:56, Alex Bligh ha scritto:
> 
> On 29 Jul 2014, at 14:42, Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
>> Il 29/07/2014 15:39, Alex Bligh ha scritto:
>>>>> I'm not sure either.  You could simply package the 12.04 ipxe ROMs into
>>>>> 14.04, and add a note about getting the sources for GPL friendliness.
>>> This would be my preference (or in Ubuntu's case, add it to the ipxe-qemu
>>> package) but I think it should only be used when the legacy machine type
>>> is used or it will break inbound migrations from other 14.04 machines
>>> started with 128k ROMs (AIUI).
>>
>> "-M pc" and its alias "-M pc-i440fx-2.0" doesn't use pxe-virtio.rom at
>> all (at least upstream).
> 
> Really? How does it pxeboot on virtio then (it definitely does pxeboot
> on virtio)?

efi-virtio.rom contains both BIOS and UEFI ROMs.

>>  Does Ubuntu 14.04 have efi-virtio.rom?
> 
> Yes. After 2 layers of symlinks you get to.
> 
> ubuntu@trustytest:~$ ls -la /usr/lib/ipxe/qemu/efi-virtio.rom
> -rw-r--r-- 1 root root 220672 Jan  6  2014 /usr/lib/ipxe/qemu/efi-virtio.rom
> 
>> It would break "-M pc-1.0" started on older 14.04, but I think that's
>> acceptable.
> 
> I was more worried about any previous versions of Ubuntu (newer than
> 12.04) which might also be using the larger rom size. But then I
> haven't investigated at what stage the rom size grew.

You're right, but in Serge's shoes I wouldn't bother about anything
except LTS.

Paolo